Fluid pressure device



, 3 Sheets-g 1 A. BOWDEN ET AL FLUID PRESSURE DEVICE une 9 1948 //p i ll3' Feb. 6, 1951 T. A. BOWDEN ET AL FLUID PRESSURE DEVICE 3 Sheets-Sheet2 Filed June 9, 1948 Zenye/ Feb. 6, 1951 T. A. BOWDEN ET AL FLUIDPRESSURE DEVICE 3 Sheets-Sheet 3 Filed June 9, 1948 cates through avalve passage 25 with a chamber B in the main cylinder at the upper endof the main piston. The passage 24 is controlled by a spring closedcheck valve 26 which permits flow of air only from the chamber A intothe cylinder II, while the passage 25 is controlled by a ball checkvalve 21 that permits passage of air onlyfrom the cylinder II into thechamber B. e

Normally there is aduantity of oil in the chamber I2 in the main pistonrod, the level of the oil being generally indicated by the broken line28, the oil being admitted into the valve tube 20 by ducts 29 at thelower end of the chamber l2. Any air trapped in the cylinder I I belowthe piston I3 may escape through a port 30 in the wall of the cylinder II and ducts 3| through which the oil may also flow from above the piston2 into the chamber I2.

Assuming the device to be mounted on a vehicle, initially a quantity ofair under pressure will be pumped into the chamber B of the maincyllnder above the piston 2 through a charging opening Illa so as toinitially support the body of the vehicle: Normally, the piston I3 willbe in contact with the cylinder head plate I and oil will pass freelythrough the ports 2| in the valve piston 20 so as to surround thepiston. In case of sudden descent of the main cylinder I as the resultof, forexample, a depression in the road, the shock will be cushioned bythe air in the chamber B and the piston I3 and valve piston 20 will bedepressed to permit oil to flow through the ports 2| into the spaceabove the valve piston. On the rebound, upward movement of the piston I3will be retarded by the oil above the valve piston and a partial vacuumwill be created in the cylinder Il above the piston 13 to cause asnubbing action or a resilient counteraction to the rebound. At the sametime, air will be compressed in the chamber A of the main cylinder belowthe main piston and some of the compressed air will be forced throughthe passage 24 into the cylinder II above the secondary piston l3. Theoil trapped above the valve piston 20 will then slowly escape throughthe clearance be-' tween the piston rod I4 and the bearing I5 until thepressures in the cylinder II above the piston I3 and in the chamber Band at opposite sides of the valve piston 20 are equalized, after whichthe spring 23 will iorce'the hold-back or valve piston 20 and thesecondary piston I3 upwardly so as to cause displacement of air from thecylinder II above the piston into the chamber B. If the main pistonshould be forced upwardly or the main cylinder should beforceddownwardly before the secondary piston I3 has fully returned to itsnormal position, the secondary piston and the main piston 2 will movetogether at about the same speed and air-will be displaced from thecylinder II into the chamber B until the piston I3 contacts the headplate III; then, and only then, will the valve ring 22 open to allow oilto pass throughthe valve piston 20 to the upper side thereof inreadiness for the snubbing action.

Thus, the device constitutes a pump which is operative incident to andduring running of the I vehicle to supply compressed air to the chamberI I, which depends upon the extent of movement of the main cylinder I asthe result of roadway roughness.

In case the pressure in the chamber A below the main piston 2 becomesless than atmospheric pressure, acheck valve 32 in the head plate 4 willopen to permit air to enter said chamber. Should the pressure becomeexcessive in said chamber A, for example, ten (10) pounds aboveatmospheric pressure, a spring closed vent valve 33- will automaticallyopen to release the surplus pressure.

In case of unusually severe rebound, the main piston 2 willclose thevent port 33 so as to build up pressure in the chamberA and provide asupplemental air cushion.

Where the invention is being used as a spring support for a vehicle andthe distance between the points of connection 6 and I of the fluidpressure device with the axle and vehicle body, re-

2 which normallycloses a duct 35 through the piston and has its lowerend reduced and projecting beyond the bottom of the piston, as indicatedat 36, to cooperate with a lever 31 having one end pivoted on the pistonand its other end adapted to engage the bottom wall of the chamber Awhen the piston B moves too close to said wall. operate at the desiredpoint by a set screw 38.

In operation, when the free end of the lever .3! engages the bottom wallof the chamber A, further relative movement of the piston 2 and the maincylinder tending to bring the piston nearer the" head plate 4, willcause actuation of the lever 1 so as to open the valve 34 and permitescape of fluid pressure from the chamber A to the chamber B. This willpermit the piston and cylinder to move to their normal relation.

The valve structure may be of any suitable type, but as shown, the valve34 is slidably mountf ed in a casing 40 which is screwed into the pistonand has a hole 4I in its outer end covered by a screen 42 to prevent thesolid matter in the oil above the piston from entering the valvepassage,"

a spring 43 being interposed between the end of the casing 49 and thevalve 34.

Preferably a lateral duct 44 is provided in the" piston between thevalve duct 35 and a felt lubricating ring 45 to conduct oil from theupper side of the piston to the contacting surfacespf the piston and thecylinder.

The valves 26 and 21 may also be mounted in the head plate In in anysuitable way, but as shown, the two valves are carried by a plug 46.that has tapered outer surfaces 41 tightly engaging correspondinglytapered surfaces in the head plate I0, the plug being separably securedto the head plate by cap screws 48.

As hereinbefore stated, the invention may also' be embodied in avariable stroke air compressor, and such an embodiment is shown inFigures 9- 12, inclusive, where the reference character 49 designatesthe main cylinder in'which is reciprocable the main piston 50 whosepiston rod 5] is slidable through the head plate 52 and has a chamber 53at its inner end in which is relatively reciprocable the secondarycylinder 54 in which in turn is reciprocable the secondary piston '55whose rod ,56 is slidable through a bearing 51 in the upper end of avalve tube 58 that iscoaxiali with the chamber 53. This valve tube isclosed;

at its low d n seeme 9 t e D s ant This lever is normally adjusted topiston, a secondary cylinder carried by said main reel prin -t! iet i,"

2. i e u-rrcqr nd c the s eoesier ev n er 5,4, lis en: 5 qmmue e t sshPI, g taway the min the P odem! belowthe piston 50, and said pass e seres closed heek a e it t. hreds P9 th lcbeels: a e 25: W n with he. recthe condary c hasseq y. Pi t n 55 l s c ntrl l d y a ball arr es o ardrqm the but my et Pa sinwa ,rt s onn c ed by a su te]: J ei ng" te ts);pmnres r an ds is om he ntetwhich ompressed or us d d a be heek-1 e ens; m pi a r r the ei stant into he port. it. Al alth mai nd r above-thpis on isco ect by a et U W the s ort; 1 am h valve alco tr lle port 131i-k heva'1ver0rt .321. is; p yided to, permit atmospheric. air to;enter the main cylinder below the piston:

'EEhe chamber 53 willcontain av quantity of" oil the level of whichpreferably will be slightly, above the upper end of the main piston 58,anda duct -'l2--wi1l permit the flow of some ofsaid oil from the chamber53' into thgvalve tube 58.

The operation or the; deyiceis substantially the samea's thathereinbefore described except that compressed air aboye themain. pistonand the secondary piston is forced into a receiver or to: some otherpointof use.

The main advantage of this structureis that it Permits ai t be compresed wherethe stroke of the relatively reciprocable piston and cylinderis,, variable. For example, such adevicemightl el-lniqmit dhet the body.ndar f ease:- tomobile so that relative movement of the body and axlecould be used to compress air for any desired purpose, for example, intoa receiver for inflating tires. Other uses of the compressor will occurto those skilled in the art.

Having thus described the invention, what we claim is: p

1. A fluid pressure device comprising a main piston, a main cylinder inwhich said main pis- 0.5 ton is relatively slidable and having an upperair chamber at one end and a lower air chamber at its other end, asecondary piston carried by and movable with and relatively to said maincylinder and in which said secondary piston is relatively slidable,there being a secondary air chamber in said secondary cylinder at oneend of said secondary piston, at least one small passage between saidsecondary chamber and said lower chamber, and a check Valve therefor topermit flow of air from said lower chamber to said secondary chamberupon relative movement of said main cylinder and said main piston in onedirection, at least one small passage between said upper chamber andsaid secondary chamber, and a check valve therefor to permit flow of airfrom said secondary chamber into said upper chamber upon relativemovement of said main cylinder and said main piston in the '15 erettaperate dir ction means. normally yieldineis nfluenc ng; Said econdarrpistonhin the; dire:-

flan tQiQl-i e air; from, said,- secondary chamber;

and meansv yieldingly retarding. movements of said secondary piston: in:said, direction and c mentioned direction under the," influence ofre/1a; tive; movement: of; said main: cylinder: and-.imaini Pistonsavalve piston rod; connecting said valve piston to said secondarypiston, aguide in the upper-end: of said valve cylinder below the levelof'said: liquid: through which said valve piston rod: is;looselyslidableto permit slow flow of liquid from said valve cylinderabove said valve" piston.

A fluid pressure device comprising amain piston amaincylinder in -whichsaid main piston. is relatively; slidable and having an upper airchamber at one end: and a; lower' air chamber at; its other end, a.secondary piston carried" and movable with and relatively to said; manpiston, a secondary cylindercarried by said mm; cylinder and in whichsaid secondary piston relatively slidable, therc bei-ng' a secondaryairchamber said secondary cylinder at one and of: said; secondary:piston, means establishingcommunication between said secondary airchamber; and. said upper and lower chambers in:., the maincylinderuponrelative movement oflsaid main-cylinder andsaid'main piston opposite:directions; respectively, means for normal'ly influencing saidsecondary: piston in one;

direction relatively mend:- main piston; means; for; yielding]direction, the last-named means comprising a hydraulic valve cylinderhaving liquid therein in said main piston and a valve piston connectedto said secondary piston and reciprocable in said valve cylinder andhaving valved ports therethrough that are automatically closed uponmovement of said secondary piston in the firstmentioned direction underthe influence of rela tive movement of said main piston and said maincylinder.

4. A fluid pressure device comprising a main piston, 51, main cylinderin which said main pie-- ton is relatively slidable and having an upper;

air chamber at one end and a lower air chamher at its other end, a,secondary piston carried:

by and movable with and relatively tosaid maim piston, a secondarycylinder carried by said main cylinder and in which said secondarypiston is:

relatively slidable, there being a secondary air chamber in saidsecondary cylinder at one end of said secondary piston, meansestablishingcommunication between said secondary air chainher and saidupper and lower chambers in the.- main cylinder upon relative movementof said main cylinder and said main piston in opposite directions,respectively, means for normally in-- fluencing said secondary piston inone direction;

rnlntivnlv in cniri main nil-LA...

retarding such movement-"- o asa d; secondary: p1ston-andifor permittingfree:- moyement: or-saidz secondary piston in: the: other? yieldinglyretarding-such movement of said secondary piston and forpermitting freemovement of said secondary piston in the other direction, the

last-named means comprising a hydraulic valve cylinder having liquidtherein in said main piston and a valve piston reciprocable insaidvalve, cylinder, a piston rod connecting saidsecondary piston tosaidvvalvempiston a guide at oneend otgsaid valve-cylinder below" .thelevel of said liquid through which said. valve piston rod islooselyslidable. a V I 1 5. .A fluid pressure device as defined in claim3 with the addition-of a'passage through said main pistonxinto saidvalvecylinder through which: saidliquid is subjected to air pressure insaid first air chamber.

- 6. A fluid pressure device as defined in claim iwith the addition of.a, passage through saidv main; piston into said, valve cylinderthrough;-

which said liquid is subjected to air pressure in said f rst air.,chamber.

7, A fluid pressure device comprising a main piston, ,a main cylinder inwhich saidmain piston is relativelyslidable. and having an upper airchamber at one'end-and a lower air chamber at its other end, a secondarypiston carried by'and movable, with and relatively to said main piston,

a secondary cylinder carried by said main cylinder rand in which saidsecondary piston is relative ly slidable, there being a secondary airchamber in said secondary cylinderat one end of said secondary piston,means establishing, communication between said secondary air chamber andsaid upper and lowerchamberss'in the main cylinder upon relativemovement of said maincylnamed means comprising. a liquid chamberinoneendof said main; piston openinginto said upper air chamber andcontaining liquid, a valve cylinder in said liquiglfichamber havinginlets for liquid at its lower end, a valve piston reciprocable 3 a Q:insaidvalve cylinder and having ports there-f; through, a valve at theupper end oijsaid piston to close said ports upon movement of said sec-"ondary piston in the first-mentioned directionf' under the influence ofrelative movement of said main cylinder and main piston, a pistonrodconnecting'said valve piston to said secondary'pis-f ton, a guide inthe upper end of said valve cylin der below the level of said liquidthrough which said valve piston rod is loosely slidable to permit? slowflow of liquid from said valve cylinder above:- said valve piston. i 8;A fluid pressure device comprising amain piston, a main cylinder inwhich said main piston-f is relatively slidable and having an upper airfchamber at one end anda lower chamber at "its" other end, a secondarypiston carried by and movable with and relatively to said main piston; asecondary cylinder carried by said main cylin- 'der and in which saidsecondary piston is rela-' tively slidable, there being a secondary airchamber in said secondary cylinder; at one end 1' of said secondarypiston, means normally; yieldingly influencing said secondary pistonin"? "--the direction to force air from said secondary chamber, meansfor yieldingly retarding movement of said secondary piston in saiddirection and for permitting tree movement thereof in the oppositedirection, an outlet-for said secondary chamber andacheck valvetherefor, and an out-:

let for said upper chamber communicating with a common discharge passagefor said outlet of said upper chamber and secondary chamber out-.-

I wardly of said check valve, and a second check valve in said dischargepassage.

THOMAS A. I BOWDEN. v

PETER TENHYENGELV v REFERENCES CITED; I The following references are ofrecord in-theu file of this patent: UNITED STATES PATENTS Number NameDate I 2,443,616 Gruss June 22, 1948 1 2,443,730 Gruss June 22, 1948

